Nibbling tool

ABSTRACT

An improvement in a throatless nibbling tool by means of which fibrous and composition sheets may be efficiently cut and which leaves clean, sharp edges along the face of the cut. A cylindrically notched punch member reciprocates within the bore of a coaxial cylindrical die member to provide the desired omnidirectional shearing action. No supporting yoke or throat is utilized since both the punch and the die are supported for relative movement from a common end.

United States Patent Smith et al.

[451 Jan. 21, 1975 NIBBLING TOOL Inventors: Glen 11. Smith, Woodland Hills;

Clarence W. Spence, North Hollywood, both of Calif.

Lockhead Aircraft Corporation, Burbank, Calif.

Filed: Feb. 20, 1973 Appl. No.: 333,483

Assignee:

U.S. Cl 30/228, 30/241, 83/621 Int. Cl. B261) 15/00 Field of Search 30/228, 241, 242, 243;

References Cited UNITED STATES PATENTS Brenning 30/242 X Kaufmann 30/228 Leibinger 30/228 X Paquet 83/621 Primary ExaminerA1 Lawrence Smith Assistant Examiner-J. C. Peters Attorney, Agent, or FirmBi1ly G. Corber; Frank Lv Zugelter [57] ABSTRACT An improvement in a throatless nibbling tool by means of which fibrous and composition sheets may be efficiently cut and which leaves clean, sharp edges along the face of the cut. A cylindrically notched punch member reciprocates within the bore of a coaxial cylindrical die member to provide the desired omnidirectional shearing action. No supporting yoke or throat is utilized since both the punch and the die are supported for relative movement from a common end.

3 Claims, 8 Drawing Figures PATENTED JMIZ I I975 SHEEI 10F 3 FIG. 5

PATENTEI] JAN 2 1 I975 SHEET 2 OF 3 FIG-6 NIBBLING TOOL BACKGROUND OF THE INVENTION l. Field of the Invention The field of art to which the invention most likely pertains is powered sheebcutting tools generally, and more particularly, hand-held nibbling machines.

2. The Prior Art Examples of prior art devices indicative of the stateof-the-art to which this invention pertains, include US. Pat. Nos. l26,357; 2,364,334; 2,610,685; and 3,069,770.

3. Problems in the Prior Art Recently developed fiber-reinforced the desired uti- Iizing novel organic fibers, examples of which are identified as PRD-49 and Nomex, manufactured by the E. I. DuPont DeNemours & Co., Del., are replacing metallic and fiberglass parts, and the like, for weight savings desired in many components of large manufacturers. In particular, the aerospace industry is substituting these new fibrous laminates for fiberglass laminates in many applications. However, conventional manufacturing methods used in fabricating fiberglass components. such as sawing, routing, or drilling, do not produce the desired clean-cut edge when applied to these new laminates. As an example, in addition to producing ragged or frayed edges along a cut, conventional drilling techniques also causes delamination.

The fibers of these new materials do not adhere as strongly to the resin used in the laminates as do glass fibers. Cutting processes tend to separate the reinforcing fiber from its resin matrix. When not supported by the resin, these fibers are very difficult to cut because of their high tensile strength and extreme flexibility. On the other hand, glass fibers not only adhere well to the resin, but being brittle, can be machined by conventional methods and tools.

Fabrication processes involving the making of cutouts in laminates. such as holes, edging, and trimming, to desired dimensions require novel tools and techniques to prepare these new fibrous laminates. Cut-out areas must be clean; that is, without any loose or uncut protruding fibers extending into the hole on along trimmed edges. By the present invention there is provided a novel and improved shearing action with practically zero tolerance between the cutting members, as distinguished from a sawing action, thereby resulting in a clean-cut hole, or a clean-cut edge, in the abovedescribed new class of laminates.

It has also been determined that conventional manufacturing tools and methods are limited in terms of uni versality of application with respect to these new fibrous laminates. For example, conventional tools, whether stationary or portable, do not provide a full 360 relative movement between the tool and the workpiece, as is desirable to make interior cut-outs or to trim irregular outlines without swinging the tool or machine in the direction of the cut. In particular, the yoke (or throat) supporting the die in such a conventional tool prevents this universality of movement. In effect, the yoke or jaws of prior nibblers limit their use. The nibbler of the present invention eliminates such a yoke and jaws, and is hereinafter generally described as a throatless" nibbler. Furthermore, the limited extent of radius of cut afforded by conventional tools is overcome by the present invention which provides unlimited radii of cut to be obtained.

SUMMARY OF THE INVENTION This invention relates to machines for nibbling sheet materials to form cut-outs or open portions therein. or therealong, and is particularly directed to a shearing attachment for hand-held power tools, the attachment having no yoke, thus providing a 360 relative turning motion between the sheet material being cut and the attachment.

The novel geometry of the cylindrically notched reciprocating punch member and the relatively stationary coaxial die member, provides a novel and improved shearing action.

An object of this invention is to provide for the efficient, clean, and smooth cutting, shearing, or removal of sheet material constituting a non-metallic fiberreinforced composition.

A further object of the invention is to provide the capability of omnidirectional or 360cutting movement along the plane of a laminated comppsition sheet.

A still further object of the invention is to eliminate a yoke supporting the die member of a nibbling attachment so as to yield an unlimited radii of cutting on such a composition.

A further object of this invention is to eliminate threaded or loosely-remaining fibers along a cut-out or open portion, and to eliminate rough edges therealong, which otherwise remain with application of conventional tools.

Another object of this invention is to provide true portability for a nibbler attachment tool whereby a composition sheet can be worked from any angle by an efficient cutting action to achieve a clean-cut edge thereon.

These and other objects and advantages of the invention will become more apparent upon a full and complete reading of the following description, the appended claims thereto, and the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a full side elevational view of a portable nib bling machine embodying the invention.

FIG. 2 is an enlarged fragmentary view, partly in section of an attachment tool incorporating the invention in the device shown in FIG. 1.

FIG. 3 is a view taken on line 3-3 of FIG. 2.

FIGS. 4 and 5 are examples of the types of cuts obtained in the practice of the prior art and this invention, respectively.

FIG. 6 is a side elevational view, partly in section. of another embodiment of the invention.

FIG. 7 photographically illustrates the results obtained by practice of this invention as compared with that obtained by a conventional device.

FIG. 8 is a perspective view of the punch and die members shown in their cooperative positions and relative to a non-metallic sheet to-be-cut.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing in which reference characters correspond to like numerals hereinafter, reference character identifies generally a hand-held portable power tool to which the invention is readily adaptable. The device 10 comprises a pneumatic (air driven) apparatus 12 to which air under pressure is supplied through a line 13 for operating its motor (not shown), all in conventional and known fashion. A casing 14 is suitably secured at the one end of the apparatus 12 for the purpose of mounting and supporting the subject matter of this invention. A ram member 15 is slidably received in the casing 14 at a right angle to the motor shaft (not shown) of the apparatus 12. An eccentric projection 16 (FIG. 6) is operatively connected in known manner, say, by a desired ratio of gearing, to the motor shaft and couples the ram member 15 thereto. A punch member 17 is securely mounted on one end of the ram member 15 by suitable means, such as by a set screw 18, and extends forwardly of an end of the casing 14. Acircular A circular member 20 is secured to such end of the casing 14 by means of a flanged nut 21 threaded thereto. The flanged nut 21 frictionally engages a circular boss 22 protruding from along a sleeve portion 23 supporting the die member 20. Sleeve portion 23 snugly fits within the casing 14. The punch member 17 is slidably received within a bore 24 provided in the die member 20, and at the end of which bore 24, a continuous annular surface 25 (FIGS. 2, 8) is provided on the die member 20. Both the die continuous annular surface 25 and punch mem ber 17 are concentrically or coaxially mounted about an axis which is also coincident with the axis for the ram member 15 and the casing 14.

The punch member 17 comprises a cylindrical head 26 having its diameter substantially that of the bore 24, an annular notch or cylindrical neck 27 of reduced diameter, and a cylindrical body 28 having a terminal shoulder 29 (FIG. 8) to which the neck 27 is attached. The diameter of the body 28 is the same as the diameter of the head 26. In the assembly of the punch member 17 to the ram 15, the neck 27 is juxtapositioned with respect to the annular surface 25 defining the end of the bore 24. The portion of the head 26 which cooperates with surface 25 die annular surface25 comprises a circumferential marginal surface 33 (FIG. 3) disposed normal to the axis of its punch member 17. Thus, as the punch member 17 is caused to reciprocate, the required cutting or shearing action may be characterized by the juncture of the circumferential marginal surface 33 about the neck 27 and the die annular surface 25.

The preferred embodiment of the die member is that shown in FIG. 6 wherein the die member includes a shouldered base 70 integrally fashioned with the wall forming the die bore in which the punch member reciprocates. The shoulder 72 on the base 70 is firmly secured to the end of the casing 14 by the flanged nut 21.

The assembly of the nibbling attachment tool should now be apparent; however, briefly, after the punch member 17 is secured to its ram 15, the ram is slidably inserted within the casing 14. The casing 14 is then secured to the housing of the apparatus 12 in known fashion so as to cause cooperative coupling between the eccentric projection 16 and the ram 15.

The assembly and securement of the respective die members mounted about their corresponding punch members and shown in FIGS. 2 and 8 are readily performed by threading the flanged nut 2t to the casing 14 and upon the portions formed on the respective die members for engagement therewith.

In operation of the FIG. 2 embodiment, as shop air (viz., compressed air) is supplied through theline 13 to the motor of the pneumatic apparatus 12, the motors shaft rotates the eccentrically mounted projection 16. The ram 15 thus reciprocates as the projection revolves about the axis of the motor shaft. The punch member 17 likewise reciprocates within the bore 24 of its cooperating die member 20. FIG. 8 illustrates the cutting or shearing action between the continuous annular surface 25 of the die member 20 and the circumferential marginal surface 33 (FIG. 3) of the punch head 26 upon a laminated sheet 80, such as may be fabricated from PRO-49 fiber-reinforced resin composite. As the punch 17 translates in the withdrawal movement of its stroking cycle into the die member 20, the thickness of the sheet 80, inserted towards and abutting the neck 27, is caught between the surfaces 25, 33. A very quick shearing action occurs, to cleanly cut off the reinforcing fibers of the laminate and the resin forming the sheet 80.

The adaptability of an air motor, such as a Rockwell model No. 3IN-S02C, with 100 psi pressure applied 14 cubic feet/min.) to the nibbling attachment tool assures a punching cycle of well-over 2,000 strokes per minute, thus assuring a complete and sharp shearing of the fibers of the laminated sheet 80.

The material out of which the punch and die members is preferably made, to avoid heating problems as much as possible, is non-deforming AISI A10 die steel. heat treated to a Rockwell value of 55/60 in a vacuum furnace with an Argon quench. A bright finish without scale is produced by such a quench after the furnace treatment. The punch and die members may be ground to a desired size before heat treatment, and only polishing thereof is required to obtain the desired cylindrical interface clearance.

It has been determined that the maximum thickness of a laminate that can be sheared without crushing the resin out of the laminate is about one-tenth inch. Also, a maximum feed rate of the nibbler to the material, without developing a ripple along the cut, is about 175 inches per minute.

FIG. 7 is an actual photographic reproduction showing cuts made in PRD-49 fiber-reinforced laminate with the nibbler of this invention and with conventional tools. FIG. 7 shows a '12 inch nibbler cut in the upper half of the photograph and disclosing cut edges of definite, sharp, and clean dimensions. In the lower half of the photograph, a standard /4 inch router cut was made in accordance with customary practice, leaving frayed and loose uncut, protruding fibers extending from the edges.

FIGS. 4 and 5 illustrate the advantage that may be obtained with respect to turning radius of the present invention as compared to that obtained by conven' tional tools. FIG. 4 shows a cut of the shortest practical radius obtainable by use of a typical cutting tool of the prior art. Cut 92 in FIG. 5, having a substantially shorter radius than that shown in FIG. 4, was obtained by use of the instant invention. The cut 94 illustrated in FIG. 5 represents a right-angled cut, and the curvature of its comer is limited only by the curvature of a particular configured neck for the punch member. The cut-out portion 96 in FIG. 5 illustrates the varied and irregular outlines or cuts made possible by utilization of the omnidirectional characteristics of the present invention.

Pursuant to the requirements of the patent statutes, the principle of this invention has been explained and exemplified in a manner so that it can be readily practiced by those skilled in the art to which it pertains, or with which it is most nearly connected, such exemplifcation including what is presently considered to represent the best embodiments of the invention. However, it should be clearly understood that the above descriptlon and illustrations are not intended to unduly limit the scope of the appended claims, but that therefrom the invention may be practiced otherwise than as specifically described and exemplified herein, by those skilled in the art and having the benefit of this disclosure.

Therefore, what we claim as patentably novel is:

l. A nibbling tool comprising:

a circular die member having a hollow cylindrical bore and a continuous annular surface defining the exposed end of said bore;

a cylindrical punch having a driven end slidably supported within said bore for reciprocation therein,

and a shearing end extending beyond said annular surface;

a cylindrical notch in said punch interposed between said driven end and said shearing end. and in confronting juxtapositioned relationship with respect to said continuous annular surface; and

means for reciprocating said punch through a displacement sufficient to initially extend said notch beyond said annular surface and thereafter retract said notch within said bore.

2. The tool ofclaim 1 wherein said cylindrical punch comprises a right cylinder having a circumferential marginal surface parallel with said continuous annular surface.

3. The tool of claim 1 wherein said die member and said punch are supported from the same end of the nibbling tool. 

1. A nibbling tool comprising: a circular die member having a hollow cylindrical bore and a continuous annular surface defining the exposed end of said bore; a cylindrical punch having a driven end slidably supported within said bore for reciprocation therein, and a shearing end extending beyond said annular surface; a cylindrical notch in said punch interposed between said driven end and said shearing end, and in confronting juxtapositioned relationship with respect to said continuous annular surface; and means for reciprocating said punch through a displacement sufficient to initially extend said notch beyond said annular surface and thereafter retract said notch within said bore.
 2. The tool of claim 1 wherein said cylindrical punch comprises a right cylinder having a circumferential marginal surface parallel with said continuous annular surface.
 3. The tool of claim 1 wherein said die member and said punch are supported from the same end of the niBbling tool. 